麻豆传媒

麻豆传媒 Engineering Professor Dr. Amina Stoddart specializes in wastewater treatment. When the COVID-19 pandemic emerged, like many others, she actively sought out ways to utilize her expertise to aid in the crisis.

Monitoring local wastewater levels, Stoddart played a key role in the development of a rapid and highly efficient test for detecting SARS-CoV-2, the virus responsible for COVID-19. Additionally, when high-quality masks were in short supply, she worked on a technique to disinfect N95s using UV LED lights.

That project has led to exciting new research focused on using UV LEDs for municipal wastewater treatment. If the lights could disinfect masks, what about water?

Mechanical wastewater treatment involves several steps. The last stage in the process involves using UV lights to eliminate micro-organisms by disrupting their DNA. However, standard UV lights come with drawbacks. They contain mercury, posing an issue if they break. Stoddart says if the bulbs heat up, "some of the contaminants still in the wastewater can bake onto the bulb鈥� and diminish its efficacy. "They are huge lights that are on all the time, so they require a ton of energy," she adds.

Enter the UV LEDs. 鈥淭he light on your phone is an LED. If you think about that from an engineering perspective 鈥� wow! You鈥檝e got so many more design capabilities.鈥� In contrast with long, fragile, energy-intensive mercury based lights, LEDs can be clustered together, and don鈥檛 generate heat in the same way as conventional lights.

Stoddart is currently running a study using the lights in a reactor at Halifax Water鈥檚 Eastern Passage wastewater plant, which can treat about 450 litres of water a minute, or 648,000 litres a day. (The full plant treats 25 million litres daily.)

鈥淗alifax Water have attached this reactor for us, which is kind of a side stream. It pulls water into our reactor right before it hits their UV lights,鈥� where it is exposed to the LEDs, Stoddart says. So far, data shows the UV LEDs are 鈥渂etter or the same as conventional treatment.鈥�

Graduate student Bailey Reid is leading the analysis of treatment results. She says Stoddart encouraged her to pursue graduate studies, and she鈥檚 glad she was persuaded. 鈥淚鈥檓 really liking what I do. There are so many opportunities. I鈥檓 working with a reactor that鈥檚 the first in the world... I don鈥檛 know anyone doing this scale of stuff. It鈥檚 incredible.鈥�

Another of Stoddart鈥檚 students, Esther Osei-Ampong, is conducting research into the use of UV LEDs at Halifax Water鈥檚 Dartmouth Wastewater Treatment Facility.

Osei-Ampong already has a master鈥檚 in wastewater resource and environmental engineering, from the Kwame Nkrumah University of Science and Technology, in Ghana. She chose to continue her studies at 麻豆传媒, because the school 鈥渉as the facilities and resources to help me achieve my aims鈥� I want to be one of the best researchers and go back and help my country. At Dal, there is always hands-on practice,鈥� she says. 鈥淭hey make everything practical.鈥�

Her research involves working on a smaller scale than Reid, playing with different light intensities and chemical oxidants to remove organic matter from wastewater through advanced oxidation.

鈥淲e are doing this in the lab on a bench scale to see how it will work, and then we can maybe try it on a larger scale,鈥� she says.

Preliminary results show that, used with the UV LEDs, hydrogen peroxide works well at lower doses, while chlorine is most effective at higher doses, she notes, adding: 鈥淚t鈥檚 not conclusive yet, but it looks very promising.鈥�

Wastewater treatment is serious business, and new treatments have to be backed by solid evidence before going into use. Stoddart says the research is promising, but there is still a lot of work ahead to see if approaches involving UV LEDs can be ramped up to a larger scale. 鈥淵ou must control effluents into the harbour, it鈥檚 very serious. Things have to work. It can鈥檛 just be trial and error kind of stuff.鈥�